This invention relates to a seam welding apparatus and a seam welding method for seam-welding a plurality of blanks, and is intended particularly to be used in a mash-seam welding operation or in a general seam welding operation for manufacturing a member to be a part of a car body of an automobile and the like.
A seam welding operation of joining a plurality of blanks is performed by overlapping respective end portions of the blanks to be joined together, clamping the respective blanks to these positions, and thereafter, seam-welding the respective end portions of the blanks by a pair of electrode rollers of a seam welding machine with its forward movement. Thereby, a finished product made of the plurality of the blanks is manufactured, and after the welding, the seam welding machine moves backward and the clamp is released. Thereafter, in the conventional art, the finished product is hung up by being attached by suction to suction means of a carrying device in an welding area where the plurality of the blanks are seam-welded, and carried from the welding area to another area by the carrying device.
Based on the conventional art, since the finished product having a size almost equal to the total size of the blanks is hung up by being attached by suction to the suction means of the carrying device in the welding area, the welding area needs to be a space with its top open widely.
However, it is sometimes necessary to dispose various members, devices and the like for moving the seam welding machine forward/backward and for other reasons in the welding area. In such cases, it is impossible to keep the welding area to be the space with its top open widely, and it is necessary to work out ways of carrying the finished product from the welding area to the other area and disposing the various members, devices and the like which are necessary for the welding area, even when the welding area is the space in the above condition.
An object of the present invention is to provide a seam welding method and a seam welding apparatus for carrying out the welding method, which is capable of carrying the finished product made of the plurality of the blanks from the welding area to the other area, even though the various members and devices which are necessary for the area are disposed in the welding area for seam-welding the plurality of the blanks.
A seam welding apparatus according to the present invention comprises a transfer table having a jig member for putting a plurality of blanks thereon and being movable between a standby area and an welding area, a moving device to allow the transfer table to reciprocate horizontally between the standby area and the welding area, a clamping device disposed in the welding area for clamping the plurality of the blanks with these end portions overlapped one another in positional relations for seam-welding the respective end portions in the welding area, and a seam welding machine being movable forward/backward to the welding area for seam-welding the respective end portions.
According to the seam welding apparatus, the plurality of the blanks to be seam-welded are put on the jig member on the transfer table and sent from the standby area to the welding area, and after the seam welding, a finished product made of the plurality of the blanks is similarly put on the jig member on the transfer table and returned to the standby area. Further, the transfer table horizontally reciprocates between the standby area and the welding area by the moving device.
Therefore, even when various members, devices and the like which are necessary for moving the seam welding machine forward/backward and for other reasons are disposed in the welding area, and hence the welding area becomes a space without its top open widely, it becomes possible to send the plurality of the blanks into the welding area and to send the finished product made of the blanks out of the welding area, and to dispose the members, devices and the like which are necessary for the welding area.
Moreover, in the seam welding apparatus, the finished product which is manufactured in the welding area by the plurality of the blanks is returned to its original standby area from which the blanks are sent to the welding area so that an opposite area to the standby area with the welding area therebetween can be freely used.
When a temporary clamping device for temporarily clamping the plurality of the blanks is disposed on the transfer table of the seam welding apparatus according to the present invention, the plurality of the blanks can be temporarily clamped before these are sent from the standby area to the welding area by the transfer table, and hence the plurality of the blanks which are sent to the welding area while being temporarily clamped can be permanently clamped by the aforesaid clamping device and seam-welded in the welding area.
Further, when a lapping device for overlapping the respective end portions of the plurality of the blanks to be seam-welded is disposed to the transfer table of the seam welding apparatus, it is possible to temporarily clamp the blanks by the temporary clamping device after the respective end portions of the plurality of the blanks are overlapped by the lapping device in the welding area.
Thereby, it becomes unnecessary to dispose the lapping device in the welding area, and hence the many more members, devices and the like of various kinds which are necessary for the seam welding can be disposed in the welding area.
Moreover, with the seam welding apparatus according to the present invention, there are two of the jig members provided on the transfer table for putting the plurality of the blanks thereon and disposed with a gap therebetween, and a position of the gap when the transfer table reaches the welding area and stops therein corresponds to a position in which the seam welding machine moves forward/backward, and an electrode roller lying-on member with a part thereof projecting into the gap is disposed on at least one of the two jig members, and the electrode roller lying-on member onto which an upper electrode roller lies, out of two upper/lower electrode rollers of the seam welding machine for seam-welding the respective end portions of the plurality of the blanks, is disposed at a position opposing to at least one of start part side and end part side of welding of the plurality of the blanks.
According to the electrode roller lying-on member, when the electrode roller lying-on member is disposed at the position opposing to the start part side of the welding, the two upper/lower electrode rollers abut against the lying-on member and move to the overlapped end portions of the plurality of the blanks to start the seam welding by pressurizing the end portions. Meanwhile, when the electrode roller lying-on member is disposed at the position opposing to the end part side of the welding, the two upper/lower electrode rollers move to the lying-on member after pressurizing the overlapped end portions of the plurality of the blanks to complete the seam welding. Therefore, the start part and the end part of the welding of the respective end portions of the plurality of the blanks can be prevented from being mashed and deformed.
It is suitable to provide one transfer table of the seam welding apparatus according to the present invention. It is also suitable that the standby areas are disposed at two spots of both sides of the welding area, the two transfer tables are provided, and the moving device allows one of the transfer tables to reciprocate between one of the two standby areas and the welding area and the other transfer table to reciprocate between the other standby area and the welding area.
When there are two transfer tables, the seam welding operation can be performed efficiently by making good use of the transfer tables.
The upper electrode roller out of the two upper/lower electrode rollers of the seam welding machine of the seam welding apparatus is pressed downwardly by pressing means for pressurizing the overlapped end portions of the plurality of the blanks. A structure is disposed in the welding area in which the seam welding machine moves forward/backward and upward reactive force occurring when the upper electrode roller is pressed downwardly by the pressing means is received by the structure.
Thereby, it is not necessary to provide a C-shaped frame having high strength for supporting the upward reactive force to the seam welding machine itself. Therefore, it is possible to make the total weight of the seam welding apparatus lighter.
In the seam welding apparatus, the pressing means for pressing the upper electrode roller downwardly may be a cylinder, a solenoid, a spring or a feed screw, and may be one combining at least two of the above.
Moreover, in the seam welding apparatus, it is suitable to provide at least one guide rail extending in a forward/backward direction of the seam welding machine to guide its forward/backward movement to the structure, and to allow the upward reactive force to act on the guide rail.
Thereby, a member of the structure for receiving the upward reactive force and a member for guiding the forward/backward movement of the seam welding machine are shared with one another, and the forward/backward movement of the seam welding machine can be performed while supporting the upward reactive force by the member of the structure which is disposed in the welding area.
The structure disposed in the welding area can be freely structured as long as it can receive the upward reactive force. As an example, the structure is formed by including a plurality of columns being provided to stand and spaced out in a forward/backward direction of the seam welding machine and a beam being provided suspendedly between upper ends of the columns.
Thus, the shape of the structure can be simply formed by the columns and the beam, and it can be structured to be able to support effectively the upward reactive force with high strength. Further, when the aforesaid guide rail onto which the upward reactive force acts is provided to the structure, the guide rail can be attached to the beam.
Furthermore, the clamping device for clamping the plurality of the blanks with these end portions overlapping one another in the welding area can be attached to the structure.
Being structured as above, the clamping device which is necessary for clamping the plurality of the blanks with these end portions overlapping one another in the seam welding as they are, and must be disposed in the welding area, can be disposed in the welding area by utilizing the structure. Further, the reactive force of the clamp occurs to the clamping device when the blanks are clamped, and the reactive force of the clamp can be effectively supported by the structure having high strength.
In the welding area, detecting means is disposed for detecting lapping amounts of the overlapped end portions of the plurality of the blanks before the seam welding is performed.
Thereby, the lapping amounts of the respective end portions of the plurality of the blanks before the seam welding can be automatically detected by the detecting means. When the detected lapping amounts are the amounts within allowance, the seam welding apparatus continues its automatic operation to perform the seam welding operation, and as this result, it is possible to manufacture the finished product with a predetermined seam welding strength. When the detected lapping amounts include an error exceeding the allowance, the seam welding apparatus can be stopped to perform an operation of changing the lapping amount to a value within the allowance.
The detecting means of the lapping amount may be a contacting type in which a contacting member such as a finger touches the blanks, but it is preferable to provide a non-contacting type using photographing means such as a camera and electrical means such as a capacitor.
When the non-contacting type detecting means of the lapping amount is used, a problem such as an wear-out of the detecting means can be prevented from occurring.
When using the camera as the detecting means, it is suitable to dispose the two cameras at both edges of the end portions of the plurality of the blanks to be seam-welded on forward/backward sides in a traveling direction of the seam welding machine so that the cameras detect the lapping amounts at the both edges thereof.
Thereby, it is possible to detect by the two cameras whether the lapping amounts of the linearly extending end portions of the plurality of the blanks across the whole length thereof are within a predetermined range or not.
In the above case, it is suitable to dispose the two cameras in a gap between the two jig members which are provided on the transfer table for putting the plurality of the blanks thereon, thereby detecting the lapping amounts.
Thus, the lapping amounts can be detected by effectively utilizing the gap between the two jig members as disposing positions of the cameras.
Further, when the detecting means of the lapping amounts are a plurality of cameras, the cameras may make a pair with two of these being disposed to upper/lower sides of the plurality of the blanks.
By providing a plurality of the pairs of the cameras in the traveling direction of the seam welding machine, the overlapping amounts can be detected at plural positions in an extending direction of the end portions of the blanks.
The detecting means of the overlapping amount may be disposed fixedly at a predetermined position in the welding area, but may be movable forward to and backward from the blanks to be seam-welded, and perform a detecting operation by moving forward when detecting the lapping amount.
Thereby, by moving the detecting means backward when the plurality of the blanks are sent to the welding area by the transfer table, the blanks are sent by the transfer table without being obstructed by the detecting means.
When the plurality of the blanks to be seam-welded by the aforesaid seam welding machine are two blanks with different thicknesses, protrusion forming means for forming a protrusion in the blank with smaller thickness is disposed in the welding area.
When the finished product is manufactured by the seam welding of the two blanks, the protrusion forming means forms the protrusion in the blank with smaller thickness which forms the finished product. Thereby, when the manufactured finished products in a multiple number are multi-tiered in an area other than the welding area, heights of the blanks with larger thickness and the blanks with smaller thickness in the finished products become equal or almost equal to each other due to the protrusions, and the finished products are in a horizontal state or almost horizontal state as a whole, and hence the uppermost finished product can be sucked and carried successively by carrying means which includes suction instruments at positions corresponding to the blanks.
The protrusion forming means can be operated every time the finished product is manufactured by the two blanks being seam-welded by the seam welding machine, or it can be operated every time a predetermined number of the finished products are manufactured by the two blanks.
In the latter case, the finished products with the formation of the protrusions and the finished products without the formation of the protrusions exist in the multi-tiered finished products, and the finished products without the formation of the protrusions exist between the finished products with the formation of the protrusions. Therefore, it can be prevented that the respective protrusions fit to each other to lower the height in the area of the blanks with smaller thickness, even though the protrusions have shapes which protrude downwardly and have hollows on its upper surfaces.
A driving force of the protrusion forming member for forming the protrusion in the blanks with smaller thickness may be generated by a cylinder or a solenoid, and its structure, form and the like are optional.
A seam welding method according to the present invention comprises the steps of supplying a plurality of blanks to the standby area, sending horizontally the blanks from the standby area to the welding area, clamping the plurality of the blanks with these end portions overlapping one another in positional relations for seam-welding the respective end portions, seam-welding the respective end portions by the seam welding machine in the welding area, releasing the clamp thereafter, returning horizontally a finished product made of the plurality of the blanks from the welding area to the standby area, and carrying the finished product from the standby area to another area.
According to the seam welding method, the plurality of the blanks to be seam-welded to become the finished product are horizontally sent from the standby area to the welding area, and after the seam welding, the finished product made of the plurality of the blanks is horizontally returned from the welding area to the standby area. Hence, it is unnecessary to prepare the space with its top open widely for the welding area, different from the case of sucking and hanging up the finished product by the suction means of the carrying device in the welding area. Therefore, the various members, devices and the like which are necessary for moving the seam welding machine forward/backward and for other reasons can be effectively disposed in the welding area, and the structure of the welding area in the entire seam welding apparatus which is structured by including the seam welding machine can be freely designed.
Moreover, in the seam welding apparatus, the finished product which is manufactured in the welding area by the plurality of the blanks is returned to its original standby area from which the blanks are sent to the welding area, and hence it is possible to freely use the opposite area to the standby area with the welding area therebetween.
In the seam welding method, it is suitable that the respective end portions of the plurality of the blanks are not overlapping and hence the blanks are not clamped when they are sent from the standby area to the welding area, and the respective end portions of the blanks are overlapping to be clamped for the seam welding after the plurality of the blanks are sent to the welding area. Meanwhile, it is also suitable that the respective end portions of the plurality of the blanks are overlapping and temporarily clamped in the standby area, and the plurality of the blanks are sent to the welding area while being temporarily clamped to be subjected to a permanent clamp as the aforesaid step of clamping in the welding area.
In the latter case, an operation of overlapping the respective end portions of the blanks for the seam welding can be performed beforehand in the standby area, not in the welding area, and it becomes unnecessary to dispose the lapping device for this lapping operation in the welding area. Therefore, the various members, devices and the like for moving the seam welding machine forward/backward and for other reasons can be disposed in the welding area in a more effective manner.
Further, it is suitable to return the finished product without clamping it when the finished product which is manufactured in the welding area is returned from the welding area to the standby area, but in case the blanks are temporarily clamped by the temporary clamping device when the plurality of the blanks are sent from the standby area to the welding area, it is also suitable to return the finished product from the welding area to the standby area while clamping the finished product by the temporary clamping device.
Thereby, the finished product can be returned from the welding area to the standby area while maintaining its position at a predetermined position because of the clamp by the temporary clamping device, and a positioning of the finished product which is necessary when the finished product is sent from the standby area to the other area can be operated.
Further, when the plurality of the blanks are temporarily clamped in the welding area like the above, it is suitable that the standby areas are disposed at two spots of both sides of the welding area, and in permanently clamping and seam-welding in the welding area the plurality of the blanks temporarily clamped in one standby area, a plurality of blanks to be succeedingly subjected to the seam welding are temporarily clamped in the other standby area, and the finished product made of the plurality of the blanks being seam-welded in the welding area is returned from the welding area to the one standby area after releasing the permanent clamp, and in sending the plurality of the blanks temporarily clamped in the other standby area to the welding area for the permanent clamp and seam-welding the blanks in the welding area, a plurality of blanks to be succeedingly subjected to the seam welding are temporarily clamped in the one standby area, and the finished product made of the plurality of the blanks being seam-welded in the welding area is returned from the welding area to the other standby area after releasing the permanent clamp, and the plurality of the blanks temporarily clamped in the one standby area are sent to the welding area for the permanent clamp, and the above operations are repeated.
Thus, when the seam welding operation is continuously performed by sending the plurality of the blanks from the two standby areas to the welding area by turns, the overlapping operation of the respective end portions of the plurality of the blanks to be succeedingly seam-welded and the temporary clamping operation thereof can be performed beforehand while the seam welding operation of the plurality of the blanks is performed in the welding area, which makes it possible to increase a number of the finished products which can be manufactured in a predetermined time and to improve manufacturing efficiency.
When the plurality of the blanks which are seam-welded in the welding area are the two blanks with different thicknesses, the protrusion forming means forms the protrusion in the blank with smaller thickness out of the two blanks after being seam-welded by the seam welding machine with its forward movement, when the seam welding machine is moving to return to its backward position.
Since the protrusion forming means forms the protrusion in the blank with smaller thickness by utilizing the time when the seam welding machine is moving back to its backward position after the seam welding machine moves forward to complete the seam welding, the working time can be effectively utilized and the entire working time is not lengthened.
When the finished products which are made of the two blanks by the seam welding are multi-tiered in an area other than the welding area, and the protrusions which are formed by the protrusion forming means in the blanks with smaller thickness protrude downwardly and have hollows on their upper surfaces, the protrusions are formed by the protrusion forming means every time the finished products of the predetermined number are manufactured.
Thereby, it can be prevented that the respective protrusions fit to each other to lower the height in the area of the blanks with smaller thickness.
The seam welding by the seam welding machine according to the present invention may be a mash-seam welding which mashes the overlapped end portions of the plurality of the blanks, or may be a normal seam welding which does not mash these